I was playing my bass guitar in marching band and it was snowing. I knew it was bad, but I got home and played it, and it was fine. A couple months later, I was playing at a basketball game, and it stopped working. I assumed it was the 9-volt battery, so I replaced it, but it still doesn't work. It's been a over a full year and I haven't taken my bass to a repair shop yet, I'm not sure that it's not the battery, because I got an old one, but I'm almost certain it was the snow getting in the pick ups.

just to be sure, try another battery. if that doesn't work just take it to a shop. it will reduce the risk of you damaging any of the wiring if you try and have a tinker yourself. i'm assuming after a year the snow would have melted so there might be some rusting in some place or another, but yeah take it to a shop rather than fiddling around in there yourself.

This almost looks like a wind up. If your bass worked the day after the snow it wasn't the snow. You have a battery in there that you think might not be working and you haven't changed it yet? Try a battery in something else to check it is working then try it in your bass. Try swapping leads too. If it isn't working then off to a tech with it.

In the front ensemble (pit) with the stand still percussion. Back in the olden days before that was allowed/the norm it was done on occasionally. You'd have your bass player, but there would also be a guy to cart around the amp and a generator to power it.